Liquid crystal display including a mainpixel electrode

ABSTRACT

A liquid crystal display including first and second substrates with a liquid crystal layer therebetween. The first substrate includes a semiconductor layer electrode electrically connected to a first source line on a first side of a position where the semiconductor layer intersects with a gate wire in a second direction, and to a contact portion on a second side of the position. A contact portion is arranged nearer the gate line than the main pixel electrode. The main pixel electrode extends from the contact portion in the second direction and is located nearer the second side than the first side. The contact portion is connected to the main pixel electrode only by a first portion of the main pixel electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2011-176090, filed Aug. 11, 2011, theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a liquid crystaldisplay.

BACKGROUND

In recent years, every effort has been made to develop flat-paneldisplays. In particular, liquid crystal displays have been attractingattention due to the advantages thereof such as reduced weights,thicknesses, and power consumption. In particular, in connection withactive matrix liquid crystal displays in which a switching element isincorporated in each pixel, a structure that utilizes lateral electricfields (including fringe electric fields) has been gathering attention,for example, a structure based on an IPS (In-Plane Switching) mode or anFFS (Fringe Field Switching) mode. A liquid crystal display in thelateral electric field mode comprises pixel electrodes and counterelectrodes formed on an array substrate and switches liquid crystalmolecules using electric lateral fields that are almost parallel to theprincipal surface of the array substrate.

On the other hand, a technique has been proposed which switches theliquid crystal molecules by forming lateral electric fields or obliqueelectric fields between pixel electrodes formed on an array substrateand counter electrodes formed on a counter substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically showing a configuration of a liquidcrystal display according to the present embodiment and an equivalentcircuit;

FIG. 2 is a plan view schematically showing an example of structure ofone pixel in the liquid crystal display panel shown in FIG. 1 as seenfrom a counter substrate side;

FIG. 3 is a cross-sectional view taken along line in FIG. 2 andschematically showing a cross-sectional structure of an array substratein the liquid crystal display shown in FIG. 2;

FIG. 4 is a cross-sectional view taken along line A-A in FIG. 2 andschematically showing a cross-sectional structure of the liquid crystaldisplay panel shown in FIG. 2;

FIG. 5 is a diagram illustrating electric fields generated between apixel electrode and a common electrode in the liquid crystal displaypanel shown in FIG. 2, and the relationship between transmittance and adirector of each liquid crystal molecule based on the electric fields;

FIG. 6 is a plan view schematically showing another example of structureof one pixel in the liquid crystal display panel shown in FIG. 1 as seenfrom the counter substrate;

FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6 andschematically showing a cross-sectional structure of an array substratein the liquid crystal display panel shown in FIG. 6;

FIG. 8 is a plan view schematically showing another example of structureof one pixel in the liquid crystal display panel shown in FIG. 1 as seenfrom the counter substrate side;

FIG. 9 is a plan view schematically showing another example of structureof one pixel in the liquid crystal display panel shown in FIG. 1 as seenfrom the counter substrate side;

FIG. 10 is a plan view schematically showing another example ofstructure of one pixel in the liquid crystal display panel provided witha second main common electrode and a second secondary common electrodeas seen from the counter substrate side; and

FIG. 11 is a plan view schematically showing another example ofstructure of one pixel in the liquid crystal display panel shown in FIG.1 as seen from the counter substrate side.

DETAILED DESCRIPTION

In general, according to one embodiment, a liquid crystal displaycomprises a first substrate comprising a gate wire, a source wireintersecting with the gate wire, a pixel electrode with a contactportion and a main pixel electrode extending from the contact portion,and a semiconductor layer arranged under the source wire andintersecting with the gate wire and bending under the source wire so asto extend to below the contact portion; a second substrate arrangedopposite the array substrate and comprising main common electrodesextending substantially parallel to the main pixel electrode on eitherside of the main pixel electrode; and a liquid crystal layer comprisingliquid crystal molecules between the first substrate and the secondsubstrate. The semiconductor layer is electrically connected to thesource wire on one side of a position where the semiconductor layerintersects with the gate wire and to the contact portion on another sideof the position where the semiconductor layer intersects with the gatewire.

The present exemplary embodiment will be described below in detail withreference to the drawings. In the figures, components providing the sameor similar functions are denoted by the same reference numerals, andduplicate descriptions are omitted.

FIG. 1 is a diagram schematically showing a configuration of a liquidcrystal display according to a first embodiment and an equivalentcircuit.

That is, the liquid crystal display comprises a liquid crystal displaypanel LPN of an active matrix type. The liquid crystal display panel LPNcomprises an array substrate AR that is a first substrate, a countersubstrate CT that is a second substrate arranged opposite the arraysubstrate AR, and a liquid crystal layer LQ held between the arraysubstrate AR and the counter substrate CT. The liquid crystal displaypanel LPN comprises an active area ACT that displays images. The activearea ACT comprises a plurality of pixels PX arranged in an m×n matrix (mand n denote positive integers).

The liquid crystal display panel LPN comprises n gate wires G (G1 toGn), n auxiliary capacitance lines C (C1 to Cn), and m source wires S(S1 to Sm). The gate wires G and the auxiliary capacitance lines Cextend substantially linearly, for example, along a first direction X.The gate wires G and the auxiliary capacitance lines C are alternatelyarranged in parallel in a second direction Y intersecting with the firstdirection X. Here, the first direction X and the second direction Y aresubstantially orthogonal to each other. The source wires S intersectwith the gate wires G and the auxiliary capacitance lines C intersectwith one another. The source wires S extend substantially linearly alongthe second direction Y. The gate wires G, the auxiliary lines C, and thesource wires S need not necessarily extend linearly and may partly bend.

Each of the gate wires G is led out from the active area ACT andconnected to a gate driver GD. Each of the source wires S is led outfrom the active area ACT and connected to a source driver SD. At least apart of each of the gate driver GD and the source driver SD is formed,for example, on an array substrate AR and connected to a driving IC chip2 formed on the array substrate AR and comprising a built-in controller.

Each pixel PX comprises a switching element SW, a pixel electrode PE,and a common electrode CE. An auxiliary capacitance Cs is formed betweenthe auxiliary capacitance line C and the pixel electrode PE.Specifically, the auxiliary capacitance Cs is formed between theauxiliary capacitance line C and a semiconductor layer PS electricallyconnected to the pixel electrode PE. The auxiliary capacity line C iselectrically connected to a voltage application section VCS to which anauxiliary capacitance voltage is applied.

According to the present embodiment, the liquid crystal display panelLPN is configured such that the pixel electrodes PE are formed on thearray substrate AR, while at least some of the common electrodes CE areformed on a counter substrate CT. Liquid crystal molecules in the liquidcrystal layer LQ are switched mainly using electric fields formedbetween the pixel electrodes PE and the common electrodes CE. Theelectric fields formed between the pixel electrodes PE and the commonelectrodes CE are oblique electric fields slightly inclined to an X-Yplane or a principal surface of the substrate defined by the firstdirection X and the second direction Y (or lateral electric fieldsalmost parallel to the principal surface of the substrate).

The switching element SW comprises, for example, an n-channel thin-filmtransistor (TFT). The switching element SW is electrically connected tothe gate wire G and the source wire S. The switching element SW may beeither of a top gate type or of a bottom gate type. Furthermore, thesemiconductor layer PS in the switching element SW is formed of, forexample, polysilicon but may be formed of amorphous silicon.

The pixel electrode PE is arranged in each pixel and electricallyconnected to the switching element SW. Each common electrode CE isarranged for the pixel electrodes in a plurality of the pixels PX viathe liquid crystal layer LQ. The pixel electrodes PE and commonelectrodes CE are formed of a light-permeable conductive material, forexample, indium tin oxide (ITO) or indium zinc oxide (IZO). However,these electrodes may be formed of any other material such as aluminum.

The array substrate AR comprises an electric feeding section VS forapplying a voltage to the common electrodes CE. The electric feedingsection VS is formed, for example, outside the active area ACT. Thecommon electrodes CE are led out from the active area ACT andelectrically connected to the electric feeding section VS via aconductive member (not shown in the drawings).

FIG. 2 is a plan view schematically showing an example of structure ofone pixel in the liquid crystal display panel LPN shown in FIG. 1 asseen from the counter substrate side. FIG. 2 is a plan view of the pixelin an X-Y plane.

The illustrated pixel PX is shaped like a rectangle with the lengththereof along the first direction X shorter than the length thereofalong the second direction Y. The gate wires G1 and G2 extend along thefirst direction X. The auxiliary capacitance line C1 is located betweenthe gate wire G1 and gate wire G2, which are adjacent to each other, andextends along the first direction X. The source wires S1 and S2 extendalong the second direction Y. The pixel electrode PE is arranged betweenthe source wire S1 and source wire S2, which are adjacent to each other.Furthermore, the pixel electrode PE is positioned between the gate wireG1 and the gate wire G2.

In the illustrated example, the source wire S1 is arranged at a left endof the pixel PX, and the source wire S2 is arranged at a right end ofthe pixel PX. Strictly speaking, the source wire S1 is located so as tostride across the boundary between the pixel PX and a pixel adjacent onthe right to the pixel PX. The source wire S2 is located so as to strideacross the boundary between the pixel PX and a pixel adjacent on theright to the pixel PX. The auxiliary capacitance line C1 is arranged inthe vicinity of the gate wire G1 located in the upper side of the pixelPX.

In the illustrated example, the switching element SW comprises thesemiconductor layer PS, electrically connected between the source wireS1 and the pixel electrode PE. The semiconductor layer PS in theswitching element SW is arranged so as to extend along the source wireS1 and the auxiliary capacitance line C1 to intersect with the gate wireG1. The semiconductor layer PS is electrically connected to the sourcewire S1 via a contact hole CH3 on one side of a position where thesemiconductor layer PS intersects with the gate wire G1. Thesemiconductor layer PS is electrically connected to a drain electrode DEand the pixel electrode PE via contact holes CH1 and CH2 formed in acutout in the auxiliary capacitance line C1, on the other side of theposition where the semiconductor layer PS intersects with the gate wireG1.

That is, the semiconductor layer PS extends along the source wire S1 soas to intersect with the gate wire G1. At a position where the sourcewire S1 and the auxiliary capacitance line C1 intersect, thesemiconductor layer PS bends along the auxiliary capacitance line C1 andextends to a central portion of the pixel PX. As described above, theswitching element SW is almost prevented from sticking out from an areawhere the switching element SW overlaps the source wire S1 and an areawhere the switching element SW overlaps the auxiliary capacitance lineC1. This suppresses a decrease in the area of an aperture contributingto display.

FIG. 3 shows an example of a cross section of the array substrate ARtaken along line in FIG. 2. The array substrate AR is formed using alight-permeable first insulating substrate 10. The semiconductor layerPS is formed on a first interlayer insulating film L1 and covered with asecond interlayer insulating film L2. The gate wire G1 and the auxiliarycapacitance line C1 are formed on the second interlayer insulating filmL2 and covered with a third interlayer insulating film L3. The sourcewire S1 and the drain electrode DE of the switching element SW areformed on a third interlayer insulating film L3 and covered with afourth interlayer insulating film L4. The pixel electrode PE is formedon the fourth interlayer insulating film L4 and covered with anorientation film AL1 described below.

The semiconductor layer PS is electrically connected to the source wireS1 (source electrode SE) and the drain electrode DE via the contactholes CH1 and CH3 formed in the third interlayer insulating film L3. Thedrain electrode DE is electrically connected to the pixel electrode PEvia the contact hole CH2 formed in the fourth interlayer insulating filmL4. The semiconductor layer PS intersects with the gate wire G1 betweena position where the semiconductor layer PS is electrically connected tothe drain electrode DE through the contact hole CH1 and a position wherethe semiconductor layer PS is electrically connected to the source wireS1 through the contact hole CH3.

At a position where the semiconductor layer PS and the gate wire G1(gate electrode GE) intersect, a light blocking layer BL is formed likean island between the first interlayer insulating film L1 and the firstinsulating substrate 10. The light blocking layer BL is formed of metalsuch as Mo or Cu or a metal alloy. The light blocking layer BL is formedto be larger than the area in which the semiconductor layer PS and thegate wire G1 intersect, thus preventing possible light leakage.

The pixel electrode PE comprises a main pixel electrode PA and a contactportion PC which are electrically connected together (or integrated witheach other). The main pixel electrode PA extends linearly along thesecond direction Y from the contact portion PC to the vicinity of alower end of the pixel PX. The main pixel electrode PA is formed like aband with substantially a constant width along the first direction X.The contact portion PC is positioned in an area where the contactportion PC overlaps the auxiliary capacitance line C1. The contactportion PC is electrically connected to the semiconductor layer PS anddrain electro DE of the switching element SW via the contact holes CH1and CH2. The contact portion PC is formed to be wider than the mainpixel electrode PA.

Such a pixel electrode PE is arranged at a substantially intermediateposition between the source wire S1 and the source wire S2, that is,arranged in the middle of the pixel PX in the first direction X. Thedistance between the source wire S1 and the pixel electrode PE along thefirst direction X is substantially equivalent to the distance betweenthe source wire S2 and the pixel electrode PE along the first directionX.

The common electrode CE comprises main common electrodes CA. The maincommon electrodes CA extend, in the X-Y plane, on either side of themain pixel electrode PA linearly along the second direction Y, which issubstantially parallel to the main pixel electrode PA. Alternatively,the main common electrodes CA lie opposite the respective source wires Sand extend substantially parallel to the main pixel electrode PA. Themain common electrodes CA are formed like a band with substantially aconstant width along the first direction X.

In the illustrated example, two main common electrodes CA are arrangedparallel to each other along the first direction X and on the laterallyopposite sides of the pixel PX. In following description, fordistinction of these main common electrodes CA, the main commonelectrode in the left of FIG. 2 is denoted as CAL, and the main commonelectrode in the right of FIG. 2 is denoted as CAR. The main commonelectrode CAL lies opposite the source wire S1, and The main commonelectrode CAR lies opposite the source wire S2.

The main common electrodes CAL and CAR are electrically connectedtogether inside or outside the active area. The main common electrodeCAL is arranged at a left end of the pixel PX, and the main commonelectrode CAR is arranged at a right end of the pixel PX. Strictlyspeaking, the main common electrode CAL is arranged so as to strideacross the boundary between the pixel PX and a pixel adjacent on theleft to the pixel PX. The main common electrode CAR is arranged so as tostride across the boundary between the pixel PX and a pixel adjacent onthe right to the pixel PX.

The positional relationship between the pixel electrode PE and the maincommon electrode CA will be focused on. The pixel electrodes PE and themain common electrodes CA are alternately arranged along the firstdirection X. The pixel electrodes PE and the main common electrodes CAare arranged substantially parallel to one another. In this case, noneof the main common electrodes CA overlap the pixel electrodes PE in theX-Y plane.

That is, one pixel electrode PE is positioned between the main commonelectrode CAL and main common electrode CAR which are adjacent to eachother. In other words, the main common electrode CAL and the main commonelectrode CAR are arranged across a position immediately above the pixelelectrode PE and the either side of the pixel electrode PE. Namely, thepixel electrode PE is arranged between the main common electrode CAL andthe main common electrode CAR. Thus, the main common electrode CAL, themain pixel electrode PA, and the main common electrode CAR are arrangedin this order along the first direction X.

The pixel electrodes PE and the main common electrodes CE are arrangedat substantially constant intervals along the first direction X. Thatis, the intervals between the main common electrodes CAL and the mainpixel electrodes PA along the first direction X are substantiallyequivalent to the intervals between the main common electrodes CAR andthe main pixel electrodes PA along the first direction X.

FIG. 4 is a cross-sectional view taken along line A-A in FIG. 2 andschematically showing a cross-sectional structure of the liquid crystaldisplay panel shown in FIG. 2. FIG. 4 shows only the components requiredfor description.

A backlight 4 is arranged on a back surface side of the array substrateAR forming the liquid crystal display panel LPN. Any of various forms ofbacklights $ is applicable, and any of various light sources which use alight emitting diode (LED) or a cold cathode fluorescent lamp (CCFL) isapplicable. The structures of the backlight and the light source willnot be described in detail.

The array substrate AR is formed using a light-permeable firstinsulating substrate 10. The source wires S are formed on the interlayerinsulating film 11 (L1 to L3) and covered with the interlayer insulatingfilm 12 (L4). The gate wires and auxiliary capacitance line not shown inFIG. 4 are arranged, for example, between the first insulating substrate10 and the interlayer insulating film 11. The pixel electrodes PE areformed on the interlayer insulating film 12. Each of the pixelelectrodes PE is positioned inward of a position immediately above theadjacent source wire S.

The first orientation film AL1 is arranged on a surface of the arraysubstrate AR which is opposite to the counter substrate CT, and extendssubstantially all over the active area ACT. The first orientation filmAL1 covers the pixel electrodes PE and the like and is also arranged onthe second interlayer insulating film 12. The first orientation film AL1is formed of a material exhibiting horizontal orientation.

The array substrate AR may further comprise some of the commonelectrodes CE.

The counter electrode CT is formed using a light-permeable secondinsulating substrate 20. The counter substrate CT comprises a blackmatrix BM, color filters CF, an overcoat layer OC, the common electrodesCE, and a second orientation film AL2.

The black matrix BM forms, in a partitioning manner, the pixels PX andapertures AP that are opposite to the pixel electrodes PE. That is, theblack matrix BM is arranged opposite wiring sections such as the sourcewires S, the gate wires G, the auxiliary capacitance lines C, thecontact portions PC of the pixel electrodes PE, and the switchingelements SW. Here, FIG. 4 shows only a part of the black matrix BM whichextends along the second direction Y. However, the black matrix BM maypartly extend along the first direction X. The black matrix BM isarranged on an inner surface 20A of the second insulating substrate 20which is opposite to the array substrate AR.

The color filters CF are arranged in association with the respectivepixels PX. That is, the color filters CF are arranged at the respectiveapertures AP in the inner surface 20A of the second insulating substrate20 and partly extend over the black matrix BM. The color filters CFarranged at the respective pixels PX, which are adjacent to one anotherin the first direction X, are in different colors. For example, thecolor filters CF are formed of a resin material and colored in threeprimary colors, red, blue, and green. Red color filters CFR formed of aresin material colored in red are arranged in association with redpixels. Blue color filters CFB formed of a resin material colored inblue are arranged in association with blue pixels. Green color filtersCFG formed of a resin material colored in green are arranged inassociation with green pixels. The boundaries between the color filtersCF are positioned so as to overlap the black matrix BM.

The overcoat layer OC covers the color filters CF. The overcoat layer OCreduces the adverse effects of recesses and protrusions on surfaces ofthe color filters CF.

The common electrodes CE are formed on a side of the overcoat layer OCwhich is opposite to the array substrate AR. The distance between thecommon electrodes CE and the pixel electrodes PE along a third directionZ is substantially constant. The third direction Z is a directionorthogonal to the first direction X and the second direction Y or thenormal direction of the liquid crystal display panel LPN.

The second orientation film AL2 is arranged on a surface of the countersubstrate CT which is opposite to the array substrate AR. The secondorientation film AL2 extends substantially all over the active area ACT.The second orientation film AL2 covers the common electrodes CE, theovercoat layer OC, and the like. The second orientation film AL2 isformed of a material exhibiting horizontal orientation.

The first orientation film AL1 and the second orientation film AL2 aresubjected to an orientation process (for example, a rubbing process or aphoto-orientation process) in order to set initial orientation of liquidcrystal molecules in the liquid crystal layer LQ. The followingdirections are parallel to each other and extend in the oppositedirections or are parallel to each other and extend in the samedirection: a first orientation process direction PD1 in which the firstorientation film AL1 initially orients the liquid crystal molecules anda second orientation process direction PD2 in which the secondorientation film AL2 initially orients the liquid crystal molecules. Forexample, the first orientation process direction PD1 and the secondorientation process direction PD2 are substantially parallel to thesecond direction Y and extend in the same direction as shown in FIG. 2.

The above-described array substrate AR and counter substrate CT arearranged such that the first orientation film AL1 lies opposite thesecond orientation film AL2. In this case, for example, columnar spacersformed integrally with one of the array substrate AR and the countersubstrate CT are arranged between the first orientation film AL1 on thearray substrate AR and the second orientation film AL2 on the countersubstrate CT. This forms a predetermined cell gap, a cell gap of, forexample, 2 μm to 7 μm. The array substrate AR and the counter substrateCT are laminated together by a seal member SB located outside the activearea ACT, with the predetermined cell gap formed between the substratesAR and CT.

The liquid crystal layer LQ is held in the cell gap between the arraysubstrate AR and the counter electrode CT. The liquid crystal layer LQis arranged between the first orientation film AL1 and the secondorientation film AL2. The liquid crystal layer LQ is formed of a liquidcrystal material with positive dielectric anisotropy.

A first optical element OD1 is applied, with an adhesive or the like, toan outer surface of the array substrate AR, that is, an outer surface10B of the first insulating substrate 10 forming the array substrate AR.The first optical element OD1 is positioned opposite the back light 4 ofthe liquid crystal display panel LPN to control the polarization stateof incident light traveling from the back light 4 into the liquidcrystal display panel LPN. The first optical element OD1 includes afirst polarizing plate PL1 with a first polarizing axis (or a firstabsorption axis) AX1.

A second optical element OD2 is applied, with an adhesive or the like,to an outer surface of the counter substrate CT, that is, an outersurface 20B of the second insulating substrate 20 forming the countersubstrate CT. The second optical element OD2 is positioned on a frontsurface side of the liquid crystal display panel LPN to control thepolarization state of exit light emitted by the liquid crystal displaypanel LPN. The second optical element OD2 includes a second polarizingplate PL2 with a second polarizing axis (or a second absorption axis)AX2.

The first polarizing axis AX1 of the first polarizing plate PL1 is, forexample, in an orthogonal relationship (cross Nichol) with the secondpolarizing axis AX2 of the second polarizing plate PL2. In this case,one of the polarizing plates has the polarizing axis thereof arrangedparallel to or orthogonally with the initial orientation direction ofthe liquid crystal molecules, that is, the first orientation processdirection PD1 or the second orientation process direction PD2. If theinitial orientation direction is parallel to the second direction Y, thepolarizing axis of one of the polarizing plates is parallel to thesecond direction Y or the first direction X.

In an example shown in FIG. 2(a), the first polarizing plate PL1 isarranged such that the first polarizing axis AX1 thereof is orthogonalto the initial orientation direction (second direction Y) of the liquidcrystal molecules LM (that is, parallel to the first direction X).Furthermore, the second polarizing plate PL2 is arranged such that thesecond polarizing axis AX2 thereof is parallel to the initialorientation direction of the liquid crystal molecules LM (that is,parallel to the second direction Y).

Furthermore, in an example shown in FIG. 2(b), the second polarizingplate PL2 is arranged such that the second polarizing axis AX2 thereofis orthogonal to the initial orientation direction (second direction Y)of the liquid crystal molecules LM (that is, parallel to the firstdirection X). Additionally, the first polarizing plate PL1 is arrangedsuch that the first polarizing axis AX1 thereof is parallel to theinitial orientation direction of the liquid crystal molecules LM (thatis, parallel to the second direction Y).

Now, operations of the liquid crystal display panel LPN configured asdescribed above will be described with reference to FIG. 2 and FIG. 4.

That is, when no voltage is applied to the liquid crystal layer LQ, thatis, when no potential difference (or no electric field) is generatedbetween the pixel electrode PE and the common electrode CE (OFF state),the liquid crystal molecules LM in the liquid crystal layer LQ areorientated such that the major axis thereof is directed toward the firstorientation process direction PD1 of the first orientation film AL1 andthe second orientation process direction PD2 of the second orientationfilm AL2. The OFF state corresponds to the initial orientation state,and the orientation direction of the liquid crystal molecules LM in theOFF state corresponds to the initial orientation direction.

Strictly speaking, the liquid crystal molecules LM are not alwaysoriented parallel to the X-Y plane but are often pre-tilted. Thus, inthis case, the initial orientation direction of the liquid crystalmolecules LM corresponds to the major axis of the liquid crystalmolecules LM in the OFF state orthographically projected on the X-Yplane. For simplification of description, it is hereinafter assumed thatthe liquid crystal modules LM are oriented parallel to the X-Y plane androtate in a plane that is parallel to the X-Y plane.

In this case, the first orientation process direction PD1 and the secondorientation process direction PD2 are both substantially parallel to thesecond direction Y. In the OFF state, as shown by a dashed line in FIG.2, each of the liquid crystal molecules LM has the major axis thereofinitially oriented substantially parallel to the second direction Y.That is, the initial orientation direction of each liquid crystal moduleLM is parallel to the second direction Y (or zero degree to the seconddirection Y).

As is the case with the illustrated example, if the first orientationprocess direction PD1 and the second orientation process direction PD2are parallel to each other and extend in the same direction, then in across section of the liquid crystal layer LQ, the liquid crystalmolecules LM is oriented in a substantially horizontal direction (apre-tilt angle is substantially zero), in the vicinity of anintermediate portion of the liquid crystal layer LQ. Then, in thevicinity of the first orientation film AL1 and in the vicinity of thesecond orientation film AL2, the liquid crystal molecules are orientedat such a pre-tilt angle that the liquid crystal molecules in thesevicinities are symmetric with respect to the above-describedintermediate portion (splayed orientation).

Here, the first orientation film AL1 oriented in the first orientationprocess direction PD1 results in the initial orientation, in the firstorientation process direction PD1, of the liquid crystal molecules LM inthe vicinity of the first orientation film AL1. The second orientationfilm AL2 oriented in the second orientation process direction PD2results in the initial orientation, in the second orientation processdirection PD2, of the liquid crystal molecules LM in the vicinity of thesecond orientation film AL2. If the first orientation process directionPD1 and the second orientation process direction PD2 are parallel toeach other and extend in the same direction, the liquid crystalmolecules LM are arranged in a splayed orientation. Furthermore, asdescribed above, the following orientations are symmetric with respectto the intermediate portion of the liquid crystal layer LQ in thevertical direction: the orientation of the liquid crystal molecules LMin the vicinity of the first orientation film AL1 on the array substrateAR and the orientation of the liquid crystal molecules LM in thevicinity of the second orientation film AL2 on the counter substrate AR.Thus, optical compensation is provided even in a direction inclined tothe normal direction of the substrate. Therefore, if the firstorientation process direction PD1 and the second orientation processdirection PD2 are parallel to each other and extend in the samedirection, black display involves reduced light leakage and a highcontrast ratio can be achieved. As a result, display quality can beimproved.

If the first orientation process direction PD1 and the secondorientation process direction PD2 are parallel to each other and extendin the opposite directions, then in a cross section of the liquidcrystal layer LQ, the liquid crystal molecules LM are oriented at asubstantially uniform pre-tilt angle in the vicinity of the firstorientation film AL1, in the vicinity of the second orientation filmAL2, and in the intermediate portion of the liquid crystal layer LQ(homogenous orientation).

Back light from the backlight 4 partly passes through the firstpolarizing plate PL1 into the liquid crystal display panel LPN. Thepolarizing state of the light having entered the liquid crystal displaypanel LPN varies depending on the orientation state of the liquidcrystal molecules LM observed when the light passes through the liquidcrystal layer LQ. In the OFF state, the light having passed through theliquid crystal layer LQ is absorbed by the second polarizing plate PL2(black display).

On the other hand, when a voltage is applied to the liquid crystal layerLQ, that is, when a potential difference (or electric fields) isgenerated between the pixel electrode PE and the common electrode CE (ONstate), lateral electric fields (or oblique electric fields) that aresubstantially parallel to the substrate are generated between the pixelelectrode PE and the common electrode CE. The liquid crystal moleculesLM are affected by the electric fields and have the major axes thereofrotated in a plane substantially parallel to the X-Y plane as shown by asolid line in FIG. 2.

In the example shown in FIG. 2, the liquid crystal molecules LM in thearea between the pixel electrode PE on the array substrate AR and themain common electrode CAL on the counter substrate CT are rotatedclockwise with respect to the second direction Y and oriented toward thelower left side of FIG. 2. The liquid crystal molecules LM in the areabetween the pixel electrode PE and the main common electrode CAR arerotated counterclockwise with respect to the second direction Y andoriented toward the lower right of FIG. 2.

As described above, in each pixel PX, when electric fields are generatedbetween the pixel electrode PE and the common electrode CE, the liquidcrystal molecules LM are oriented in a plurality of directions at aposition which overlaps the pixel electrode PE and which serves as aboundary. Domains are formed in the respective orientation directions.That is, a plurality of domains are formed in one pixel PX.

In the ON state, back light traveling from the backlight 4 into theliquid crystal display panel LPN partly passes through the firstpolarizing plate PL1 into the liquid crystal display panel LPN. The backlight having entered the liquid crystal layer LQ has the polarizingstate thereof changed. In the ON state, at least part of the lighthaving passed through the liquid crystal layer LQ is transmitted throughthe second polarizing plate PL2 (white display).

FIG. 5 is a diagram illustrating electric fields generated between thepixel electrode PE and common electrode CE in the liquid crystal displaypanel LPN shown in FIG. 2, and the relationship between transmittanceand a director of each of the liquid crystal molecules LM based on theelectric fields.

In the OFF state, the liquid crystal molecules LM are initially orientedsubstantially parallel to the second direction Y. In the ON state inwhich a potential difference is generated between the pixel electrode PEand the common electrodes CE, an optical modulation rate for the liquidcrystals is highest (that is, the rate of transmission through theaperture is greatest) when the director of each of the liquid crystalmolecules LM (or the direction of the major axis of the liquid crystalmolecule LM) is displaced, in the X-Y plane, by about 45° from the firstpolarizing axis AX1 of the first polarizing plate PL1 and the secondpolarizing axis AX2 of the second polarizing plate PL2.

In the illustrated example, in the ON state, the director of the liquidcrystal molecule LM between the main common electrode CAL and the pixelelectrode PE is substantially parallel to an orientation of 45° or −225°in the X-Y plane. The director of the liquid crystal molecule LM betweenthe main common electrode CAR and the pixel electrode PE issubstantially parallel to an orientation of 135° or −315° in the X-Yplane. Then, a peak transmittance is obtained. Now, the distribution oftransmittance per pixel will be focused on. Then, the transmittance issubstantially zero over the pixel electrode PE and over the commonelectrode CE. On the other hand, a high transmittance is obtained allover the electrode gap between the pixel electrode PE and the commonelectrode CE.

The main common electrode CAL positioned immediately above the sourcewire S1 and the main common electrode CAR positioned immediately abovethe source wire S2 lie opposite to the black matrix BM. However, themain common electrodes CAL and CAR both have a width equal to or smallerthan the width of the black matrix BM along the first direction X. Thus,the main common electrodes CAL and CAR are prevented from extendingtoward the pixel electrode PE beyond the positions where the main commonelectrodes CAL and CAR overlap the black matrix BM. Thus, the aperturecontributing to display per pixel corresponds to the area between thepixel electrode PE and the main common electrode CAL and the areabetween the pixel electrode PE and the main common electrode CAR whichareas are covered by the area in each cell of the black matrix BM orbetween the source wire S1 and the source wire S2.

The present embodiment described above enables a decrease intransmittance to be suppressed. This enables degradation of the displayquality to be suppressed.

Furthermore, the present embodiment provides a high transmittance in theelectrode gap between the pixel electrode PE and the common electrodeCE. Thus, the inter-electrode distance between the pixel electrode PEand each of the main common electrodes CAL and CAR can be increased inorder to make the transmittance per pixel sufficiently high.Additionally, for a product specification with a different pixel pitch,such a peak condition for the distribution of transmittance as shown inFIG. 5 may be utilized by changing the inter-electrode distance (thatis, changing the arrangement position of the main common electrode CAwith respect to the pixel electrode PE arranged substantially in thecenter of the pixel PX). That is, in a display mode according to thepresent embodiment, product specifications ranging from those havingrelatively large pixel pitches and low resolutions to those havingrelatively small pixels pitch and high resolutions do not necessarilyrequire fine processing of electrodes. Products with various pixelpitches can be provided by appropriately setting the inter-electrodedistance. Thus, demands for a high transmittance and a high resolutioncan be easily met.

Furthermore, according to the present embodiment, as shown in FIG. 5,the distribution of transmittance in areas involving an overlap with theblack matrix BM indicates a sufficiently reduced transmittance. This isbecause electric fields are prevented from leaking beyond the positionof the common electrode CE in the pixel and because no unwanted lateralelectric field is generated in the pixels adjacent to each other acrossthe black matrix BM, so that the liquid crystal molecules in the areaswhere the common electrode overlaps the black matrix BM are kept in theinitial orientation state as in the case of the OFF state (or in theblack display state). Thus, even if the color of the color filter variesbetween the adjacent pixels, the colors can be restrained from beingmixed together. This enables degradation of color reproducibility and adecrease in contrast ratio to be suppressed.

Furthermore, when the array substrate AR and the counter substrate CTare misaligned with each other, in the first direction X, the distancebetween the pixel electrode PE and one of the common electrodes CEarranged on the either side of the pixel electrode PE may differ fromthe distance between the pixel electrode PE and the other commonelectrode CE. However, such misalignment occurs in all the pixels PX,and thus the distribution of electric fields does not vary among thepixels PX. Hence, the adverse effect of the misalignment on imagedisplay is minimized. Furthermore, even if the array substrate AR andthe counter substrate CT are misaligned with each other, unwantedleakage of electric fields to the adjacent pixels can be suppressed.Thus, even if the color of the color filter varies between the adjacentpixels, possible color mixture can be suppressed, enabling degradationof color reproducibility and a decrease in contrast ratio to berestrained.

Furthermore, according to the present embodiment, each of the maincommon electrodes CA lies opposite the source wire S. In particular, theaperture AP may be larger if the main common electrodes CAL and CAR arearranged immediately above the source wires S1 and S2, respectively,than if the main common electrodes CAL and CAR are arranged closer tothe pixel electrode PE than the source wires S1 and S2, respectively.Thus, the transmittance of the pixel PX can be increased if the maincommon electrodes CAL and CAR are arranged immediately above the sourcewires S1 and S2, respectively.

Additionally, arranging the main common electrodes CAL and CARimmediately above the source wires S1 and S2, respectively, enables anincrease in the inter-electrode distance between the pixel electrode PEand each of the common electrodes CAL and CAR. Thus, lateral electricfields that are closer to horizontal electric fields can be formed. Thisenables maintenance of increased viewing angle, which is an advantageof, for example, an IPS mode, which corresponds to a conventionalconfiguration.

In addition, the present embodiment enables a plurality of domains to beformed in a single pixel. As a result, the viewing angle can beoptically compensated for in a plurality of directions and thusincreased.

In the above-described example, the initial orientation direction of theliquid crystal molecules LM is parallel to the second direction Y.However, as shown in FIG. 2, the initial orientation direction of theliquid crystal molecules LM may be an oblique direction D that obliquelyintersects with the second direction Y. Here, an angle θ1 between theinitial orientation direction D and the second direction Y is largerthan 0° and smaller than 45°. An angle θ1 of about 5° to 30° and moredesirably at most 20° is very effective in controlling the orientationof the liquid crystal molecules LM. That is, the initial orientationdirection of the liquid crystal molecules LM is desirably substantiallyparallel to a direction that is between 0° and 20° to the seconddirection Y.

Furthermore, in the above-described example, the liquid crystal layer LQis formed of the liquid crystal material with the positive dielectricanisotropy. However, the liquid crystal layer LQ may be formed of aliquid crystal material with negative dielectric anisotropy. However,for the liquid crystal material with the negative dielectric anisotropy,which is opposite to the dielectric anisotropy of the above-describedliquid crystal material, the angle θ1 is preferably between 45° and 90°and desirably at least 70°. This will not be described in detail.

Even in the ON state, almost no lateral electric fields are generatedover the pixel electrodes PE or the common electrodes CE (or electricfields sufficient for driving the liquid crystal molecules LM are notgenerated). Consequently, the liquid crystal molecules LM are almostimmovable from the initial orientation direction as in the case of theOFF state. Thus, even if the pixel electrodes PE and the commonelectrodes CE are formed of a light-permeable conductive material suchas ITO, the back light is almost prevented from passing through theseareas and thus from contributing to display even in the ON state.Therefore, the pixel electrodes PE and the common electrodes CE need notnecessarily be formed of a transparent conductive material but may beformed of a conductive material such as aluminum, solver, or copper.

Now, a liquid crystal display apparatus according to a second embodimentwill be described with reference to the drawings. In the descriptionbelow, components similar to those in the above-described firstembodiment are denoted by the same reference numerals and will not bedescribed below.

FIG. 6 is a plan view schematically showing another example of structureof one pixel PX in which the liquid crystal display panel LPN shown inFIG. 1 is viewed from the counter substrate.

This structure example is different from the structure example shown inFIG. 2 in that the auxiliary capacitance line C is arranged in thecentral portion of the pixel PX in the second direction Y. The centralportion of the pixel PX in the second direction Y is such that thedistance between the central portion and the gate wire G1 issubstantially equal to the distance between the central portion and thegate wire G2.

That is, the pixel electrode PE comprises the main pixel electrode PAand contact portion PC electrically connected together (or integratedtogether). The main pixel electrode PA extends along the seconddirection Y linearly from the contact portion PC to the vicinity of theupper end or lower end of the pixel PX. The main pixel electrode PA isformed like a band with a substantially uniform width along the firstdirection X. The contact portion PC is arranged in an area where thecontact portion PC overlaps the auxiliary capacitance line C1, that is,in the central portion of the pixel PX in the second direction Y. Themain pixel electrode PA extends toward each of the gate wires G1 and G2.The contact portion PC is electrically connected to the semiconductorlayer PS and drain electrode DE of the switching element SW via thecontact holes CH1 and CH2. The contact portion PC is formed to be widerthan the main pixel electrode PA.

The pixel electrode PE is arranged substantially at an intermediateposition between the source wire S1 and the source wire S2, that is, inthe center of the pixel PX in the first direction X. The distancebetween the source wire S1 and the pixel electrode PE along the firstdirection X is substantially equal to the distance between the sourcewire S2 and the pixel electrode PE along the first direction X.

The positional relationship between the pixel electrode PE and thecommon electrode CE will be focused on. The main pixel electrodes PA andthe main common electrodes CA are alternately arranged along the firstdirection X. That is, one main pixel electrode PA is positioned betweenthe main common electrode CAL and main common electrode CAR which areadjacent to each other. The main common electrode CAL, the main pixelelectrode PA, and the main common electrode CAR are arranged in thisorder along the first direction X.

In the illustrated example, the switching element SW comprises thesemiconductor layer PS electrically connected to the source wire S1. Thesemiconductor layer PS of the switching element SW extends along thesource wire S1 and the auxiliary capacitance line C1. The semiconductorlayer PS is electrically connected to the drain electrode DE and thepixel electrode PE via the contact holes CH1 and CH2 formed in cutoutsobtained by partly removing the auxiliary capacitance line C1.

The switching element SW is provided in an area where the switchingelement SW overlaps the source wire E1 and in an area where theswitching element SW overlaps the auxiliary capacitance line C1. Thatis, the semiconductor layer PS extends along the source wire S1 so as tointersect with the gate wire G2. The semiconductor layer PS bends alongthe auxiliary capacitance line C1 at a position where the source wire S1and the auxiliary capacitance line C1 intersect, and extends to thecentral portion of the pixel PX. As described above, the switchingelement SW is almost prevented from sticking out from the area where theswitching element SW overlaps the source wire S1 and the area where theswitching element SW overlaps the auxiliary capacitance line C1. Thissuppresses a decrease in the area of the aperture contributing todisplay.

FIG. 7 shows an example of a cross section of the array substrate ARtaken along line VII-VII shown in FIG. 6. The array substrate AR isformed using the light-permeable first insulating substrate 10. Thesemiconductor layer PS is formed on the first interlayer insulating filmL1 and covered with the second interlayer insulating film L2. The gatewire G2 and the auxiliary capacitance line C1 are formed on the secondinterlayer insulating film L2 and covered with the third interlayerinsulating film L3. The source wire S1 and the drain electrode DE of theswitching element SW are formed on the third interlayer insulating filmL3 and covered with the fourth interlayer insulating film L4. The pixelelectrode PE is formed on the fourth interlayer insulating film L4 andcovered with the orientation film AL1 described below.

The semiconductor layer PS is electrically connected to the source wireS1 (source electrode SE) and the drain electrode DE via the contactholes CH1 and CH3 formed in the second interlayer insulating film L2 andthe third interlayer insulating film L3. The drain electrode DE iselectrically connected to the pixel electrode PE via the contact holeCH2 formed in the fourth interlayer insulating film L4.

A light blocking layer BL is arranged between the first interlayerinsulating film L1 and the first insulating substrate 10 at a positionwhere the semiconductor layer PS and the gate wire G2 (gate electrodeGE) intersect. The light blocking layer BL is formed to be larger thanthe area where the semiconductor layer PS and the gate wire G1intersect. This prevents possible optical leakage.

In the example shown in FIG. 6, the semiconductor layer PS is arrangedalong the source wire S1 so as to intersect with the lower illustratedgate wire G2. However, the semiconductor layer PS may be arranged so asto intersect with the upper illustrated gate wire G1. Moreover, thesemiconductor layer PS of the switching element SW arranged in one ofthe pixels PX that are adjacent to each other in the first direction Xmay be located so as to intersect with the lower illustrated gate wireG2. The semiconductor layer PS of the switching element SW arranged inthe other pixel PX may be located so as to intersect with the upperillustrated gate wire G1. Arranging the semiconductor layer PS asdescribed above enables a video signal supplied to the pixels PX thatare adjacent to each other in the first direction X to be inverted inpolarity between the pixels PX.

In such a structure example, the liquid crystal molecules LM initiallyoriented in the second direction Y in the OFF state are affected byelectric fields generated between the pixel electrode PE and the commonelectrode CE in the ON state. The major axis of each of the liquidcrystal molecules LM rotates in a plane that is substantially parallelto the X-Y plane, as shown by a solid line in FIG. 6.

That is, the liquid crystal molecules LM in the area between the pixelelectrode PE and the main common electrode CAL are rotated clockwisewith respect to the second direction Y and oriented toward the lowerleft side of FIG. 6. The liquid crystal molecules LM in the area betweenthe pixel electrode PE and the main common electrode CAR are rotatedcounterclockwise with respect to the second direction Y and orientedtoward the lower right side of FIG. 6.

As described above, in each pixel PX, when electric fields are generatedbetween the pixel electrode PE and the common electrode CE, the liquidcrystal molecules LM are oriented in a plurality of directions at aposition which overlaps the pixel electrode PE and which serves as aboundary. Domains are formed in the respective orientation directions.That is, a plurality of domains are formed in one pixel PX.

The liquid crystal display according to the present embodiment issimilar to the liquid crystal display according to the above-describedfirst embodiment except for the above-described configuration, and canexert effects similar to the effects of the first embodiment. That is,the present embodiment enables a decrease in transmittance to besuppressed. This enables degradation of display quality to besuppressed.

FIG. 8 is a plan view schematically showing another example of thestructure of one pixel in which the liquid crystal display panel LPNshown in FIG. 1 is viewed from the counter substrate.

This structure example is different from the structure example shown inFIG. 7 in that the width of the gate wire G in the second direction Y islarger in portions of the gate wire G in which the semiconductor layerPS and the gate wire G intersect than in the other portions of the gatewire G.

That is, according to the present embodiment, portions of the gate wireG which corresponds to the gate electrodes GE are wider, in the seconddirection Y, than the other portions of the gate wire G. This avoids adecrease in aperture area caused by the increased width of the gate wireG, while maintaining the channel length L of the switching element SW ata predetermined magnitude.

That is, the present embodiment enables a decrease in transmittance tobe suppressed without degrading performance of the switching element SW.Thus, the display quality can be restrained from being degraded.

FIG. 9 is a plan view schematically showing another example of thestructure of one pixel in which the liquid crystal display panel LPNshown in FIG. 1 is viewed from the counter substrate.

This structure example is different from the structure example shown inFIG. 7 in that the gate wire G branches at portions of the gate wire Gin which the semiconductor layer PS and the gate wire intersect so thatthe gate wire G and the semiconductor layer PS intersect at a pluralityof positions.

That is, according to the present embodiment, the gate wire G branchesinto a first gate electrode GE1 and a second gate electrode GE2 at theportions of the gate wire G in which the semiconductor layer PS and thegate wire intersect. Thus, in the example shown in FIG. 9, the switchingelement SW is a dual gate TFT with a plurality of the gate electrodesGE1 and GE2.

The switching element comprising the dual gate TFT as described aboveallows possible leakage current to be prevented and enables an increasein the withstand voltage of the switching element SW.

That is, the present embodiment enables a decrease in transmittance tobe suppressed without degrading the performance of the switching elementS. This in turn enables degradation of the display quality to besuppressed.

According to the first embodiment and the second embodiment, the commonelectrodes CE comprise only the main common electrodes CA. However, thecommon electrodes CE may comprise, besides the above-described maincommon electrodes CA, secondary common electrodes extending along thefirst direction X (not shown in the drawings). In this case, the maincommon electrodes CA and the secondary common electrodes are integrallyor contiguously formed.

Each of the secondary common electrodes is arranged opposite thecorresponding one of the gate wires G. Two common electrodes arearranged parallel to each other along the first direction X. Fordistinction of these secondary common electrodes, the secondary commonelectrode lying opposite the upper illustrated gate wire G1 is referredto as a secondary common electrode CBU, and the secondary commonelectrode lying opposite the lower illustrated gate wire G2 is referredto as a secondary common electrode CBB. The secondary common electrodeCBU is arranged at the upper end of the pixel PX opposite the gate wireG1. That is, the secondary common electrode CBU is arranged so as tostride across the pixel PX and a pixel located above and adjacent to thepixel PX. Furthermore, the secondary common electrode CBB is arranged atthe lower end of the pixel PX opposite the gate wire G2. That is, thesecondary common electrode CBB is arranged so as to stride across thepixel PX and a pixel located below and adjacent to the pixel PX.Provision of the secondary common electrodes enables the orientation ofthe liquid crystal molecules LM to be controlled at high speed.

Furthermore, according to the present embodiment, the common electrodesCE may comprise, besides the main common electrodes CA provided on thecounter substrate CT, second main common electrodes provided on thearray substrate AR opposite the main common electrodes CA (or oppositethe source wires S). The second main common electrodes extend parallelto the main common electrodes CA and have the same potential as that ofthe main common electrodes CA. Provision of the second main commonelectrodes enables unwanted electric fields from the source wires S tobe shielded.

Additionally, the common electrodes CE may comprise, besides the maincommon electrodes CA provided on the counter substrate CT, secondsecondary common electrodes provided on the array substrate AR oppositethe gate wires G and the auxiliary capacitance lines C. The secondsecondary main common electrodes extend in a direction in which thesecond secondary main common electrodes intersect with the main commonelectrodes. Moreover, the second secondary main common electrodes havethe same potential as the main common electrodes CA. Provision of thesecond secondary main common electrodes enables unwanted electric fieldsfrom the gate wires G and the auxiliary capacitance lines C to beshielded. A configuration comprising the second main common electrodesor the second secondary main common electrodes enables degradation ofthe display quality to be further prevented.

FIG. 10 is a plan view schematically showing another example of thestructure of one pixel in which the liquid crystal display panel isviewed from the counter substrate if the second main common electrodesand the second secondary main common electrodes are installed in theliquid crystal display panel. FIG. 10 does not show the switchingelement SW. The gate wire G is configured to branch as shown in FIG. 9.However, the switching element SW is not limited to the dual gateswitching element but may have any of the above-describedconfigurations.

This example involves a second main common electrode CCL lying oppositethe source wire S1, a second main common electrode CCR lying oppositethe source wire S2, a second secondary common electrode CDU lyingopposite the gate wire G1, and a second secondary common electrode CDBlying opposite the gate wire G2.

In the case illustrated in FIG. 10, the second main common electrode CCLlying opposite the source wire S1 and the second main common electrodeCCR lying opposite the source wire S2 are partly removed at the oppositesides of the contact portion PC of the pixel electrode PE in the firstdirection X. This is because if the pitch of the pixels PX is reduced asa result of increased definition, the distance between the contactportion PC and each of the second main common electrodes CCL and CCRdecreases, possibly leading to a short circuit. In this case, thedefinition of the liquid crystal display panel LPN can further beincreased by dividing each of the second secondary common electrodes CCLand CCR into two pieces in the vicinity of the contact portion PC.

As described above, the present embodiment can provide a liquid crystaldisplay that enables degradation of the display quality to besuppressed.

Several embodiments of the present invention have been described.However, the embodiments are illustrative and are not intended to limitthe scope of the present invention. These new embodiments may beimplemented in various other forms, and various omissions,substitutions, and changes may be made to the embodiments withoutdeparting from the spirits of the invention. The embodiments andvariations thereof are included in the scope and spirits of theinvention and also in the invention set forth in the claims andequivalents of the invention.

For example, according to the first embodiment and the secondembodiment, the array substrate AR comprises the auxiliary capacitancelines C. However, the auxiliary capacitance lines C may be omitted.

FIG. 11 shows the structure according to the first embodiment whichcomprises no auxiliary capacitance line C. The semiconductor layer PS ofthe switching element SW extends under the source wire S so as tointersect with the gate wire and bends under the source wire so as toextend to below the contact portion.

As described above, according to the first embodiment and the secondembodiment, lateral electric fields are generated between the pixelelectrode PE formed on the array substrate AR and the common electrodeCE formed on the counter substrate CT. To allow the lateral electricfields to be generated, the distance between the pixel electrode PE andthe common electrode CE is set at least twice as large as the thicknessof the liquid crystal layer LQ. Thus, according to the first embodimentand the second embodiment, to allow the liquid crystal molecules torespond properly to a driving voltage, the dielectric anisotropy andrelative permittivity of the liquid crystal molecules LM forming theliquid crystal layer LQ are set as follows: the dielectric anisotropy Δ∈is set to a value of between 11 and 21, the relative permittivity ∈// isset to a value of between 16 and 24, and the relative permittivity ∈⊥ isset to a value of between 3 and 5.

Experiments were conducted using the structure according to the firstand second embodiments which includes no auxiliary capacitance line Cformed therein as well as liquid crystal molecules with theabove-described dielectric anisotropy and relative permittivity. Then,proper display quality was achieved.

Even if the auxiliary capacitance lines C are omitted from structureaccording to the first and second embodiments, a decrease intransmittance and thus degradation of the display quality can besuppressed by arranging the semiconductor layer PS of the switchingelement SW so that the semiconductor layer PS extends under the sourcewire S so as to intersect with the gate wire and bends under the sourcewire so as to extend to below the contact portion.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A liquid crystal display comprising: a firstsubstrate comprising a first insulating substrate, a gate wire extendingin a first direction a first source wire extending in a second directionintersecting with the first direction, a pixel electrode with a contactportion and a main pixel electrode extending from the contact portion,and a semiconductor layer arranged under the first source wire andintersecting with the gate wire and bending under the first source wireso as to extend to below the contact portion; and a second substratearranged opposite the first substrate; a liquid crystal layer comprisingliquid crystal molecules between the first substrate and the secondsubstrate; wherein the semiconductor layer is electrically connected tothe first source wire on a first side of a position where thesemiconductor layer intersects with the gate wire in the seconddirection and to the contact portion on a second side of the position,the contact portion is arranged nearer the gate wire than the main pixelelectrode, the main pixel electrode extends from the contact portion inthe second direction and is located nearer the second side than thefirst side, and the contact portion is connected to the main pixelelectrode only by a first portion of the main pixel electrode.
 2. Theliquid crystal display according to claim 1, wherein the first substratefurther comprises an auxiliary capacitance electrode formed between thefirst insulating substrate and the pixel electrode, and the contactportion is arranged on the auxiliary capacitance electrode.
 3. Theliquid crystal display according to claim 2, wherein the auxiliarycapacitance electrode comprises an opening formed under the contactportion, and the semiconductor layer bends at a position where theauxiliary capacitance electrode and the first source wire intersect, soas to extend to below the contact portion, and the semiconductor layeris electrically connected to the contact portion at the opening.
 4. Theliquid crystal display according to claim 1, wherein the main pixelelectrode is formed in a band shape with substantially a constant widthin the first direction, and the contact portion is formed to be widerthan the main pixel electrode in the first direction.
 5. The liquidcrystal display according to claim 4, the first substrate furthercomprises a second source wire extending parallel to the first sourcewire, the pixel electrode is arranged between the first source wire andthe second source wire, and a first distance between the first sourcewire and the main pixel electrode in the first direction issubstantially equivalent to a second distance between the second sourcewire and the main pixel electrode in the first direction.
 6. The liquidcrystal display according to claim 4, wherein the first substratefurther comprises: a first insulating film interposed between the firstinsulating substrate and the semiconductor layer; and a light blockinglayer formed between the first insulating film and the first insulatingsubstrate at a position where the semiconductor layer and the gate wireintersect, and the light blocking layer is formed to be larger than anarea in which the semiconductor layer and the gate wire intersect. 7.The liquid crystal display according to claim 6, wherein the firstsubstrate further comprises: a second insulating film interposed betweenthe semiconductor layer and the gate wire; a third insulating filminterposed between the gate wire and the first source wire; a fourthinsulating film interposed between the first source wire and the pixelelectrode; a first contact hole formed in the second insulating film andthe third insulating film; a drain electrode formed on the thirdinsulating film and electrically connected to the semiconductor layerthrough the first contact hole; and a second contact hole formed in thefourth insulating film, and the pixel electrode is formed on the fourthinsulating film and electrically connected to the drain electrodethrough the second contact hole.